Re: Motor Speed Control

On 9/03/2024 5:30 am, KevinJ93 wrote:

On 3/7/24 7:18 PM, John Larkin wrote:

On Thu, 7 Mar 2024 12:13:59 -0800, KevinJ93 <kevin_es@whitedigs.com>
wrote:
>

...

>
Stepper motors are invariably of the reluctance type. With simple
drivers they have a great deal of cogging, which is undesirable in a
capstan drive motor.

>
There are two types, PM and VR. PM steppers use bipolar coil drive and
have a strong unpowered detent. And can act as generators.

 Yes, I was wrong.
 

Both can microstep nicely, for smooth motion.

 Given appropriate driving circuitry that would have been expensive and power consuming in 1970.

Nonsense. The cheap way of making an approximation to a sine wave is pulse width modulation.
https://www.tinaja.com/glib/sinquest.pdf
That document is from 1997, but the idea has been around for a lot longer. I used it in 1975 - if not to make sine waves - and it is cheap and efficient. The "modified square wave" - which has no third harmonic content - is equally old.
<snip>
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Bill Sloman, Sydney